1. Technical Field
This invention relates to a tilt hinge which can change an angle of a display portion (a movable portion) such as a liquid crystal display unit to an apparatus body (a fixed portion).
2. Background Art
In the display portion (the movable portion) such as the liquid crystal display unit, a tilt hinge is used in order to adjust the angle thereof against the apparatus body (the fixed portion).
Various tilt hinges related to the present invention are already proposed. By way of example, Japanese Unexamined Utility Model Application Publication Jikkai No. Hei 5-21080 JP-U 5-21080 (which will be also called Patent Document 1) discloses a tilt hinge for OA equipment which is capable of possibly preventing abrasion of a friction member and of preventing a stop holding ability from lowering in a use open/close angle of a display body after be used for a long time. The tilt hinge requires to stably stop and hold the display body (the movable portion) against an apparatus main body (a fixed portion) at an arbitrary position in the use opening angle. The tilt hinge disclosed in Patent Document 1 comprises a mounting member, a rotation shaft, a switch pushing member, a thrust washer and a retaining washer, and a spring washer and a retaining washer. The mounting member comprises a mounting base mounted to the apparatus main body side and a bearing plate. The rotation shaft serves as a supporting member for the display body having at one portion a small-diameter portion born to a bearing hole in the bearing plate of the mounting member. The switch pushing member is mounted to a large-diameter portion of the rotation shaft. The thrust washer and the retaining washer are sandwiched between the switch pushing member and a side surface of the bearing plate with the small diameter portion of the rotation shaft inserted thereto. The spring washer and the retaining washer are arranged to another side surface of the bearing plate with the small-diameter portion of the rotation shaft inserted thereto. The tilt hinge having such a structure is configured to rotate only when the rotation shaft is subjected to a predetermined rotation torque by riveting an end portion of the small-diameter portion.
In the tilt hinge disclosed in Patent Document 1, the bearing plate has a projecting piece projected therefrom and the switch pushing member is provided with a cam portion. When the bearing shaft together with the rotation shaft rotates, it hits on the cam portion at a predetermined rotation angle (135 degrees). That is, the cam portion of the switch pushing member serves as a stopper which is engaged with the projecting piece projected from the bearing plate.
Japanese Unexamined Patent Application Publication of Tokkai No. 2001-32823 or JP-A 2001-32823 (which will be also called Patent Document 2), which corresponds to U.S. Pat. No. 6,421,878, discloses a tilting hinge for a portable computer having a body and a display screen. The tilting hinge disclosed in Patent Document 2 comprises a fixture, a rotating shaft, a first friction washer, a second friction washer, an elastic assembly, a set washer, a calked projection, and torque changing means. The fixture consists of a fixing plate portion to be fixed to the body of the portable computer and a bearing plate portion bent perpendicularly to the fixing plate portion. The rotating shaft consists of a fixing portion to be fixed to the display screen of the portable computer, a large-diameter portion and a small-diameter portion. The rotating shaft is born relatively rotatably in a bearing hole formed in the bearing plate portion of the fixture. The first friction washer is interposed between the large-diameter portion of the rotating shaft and one side of the bearing plate. The first friction washer is engaged with the rotating shaft on the bearing plate portion of the fixture. The second friction washer is provided at another side of the bearing plate and is engaged with the rotating shaft. The elastic assembly consists of a spring washer or spring washers, a belleville spring or belleville springs, a wave washer or wave washers. The elastic assembly is disposed to abut on the second friction washer. The set washer is disposed to abut on the elastic assembly rotatably with the rotating shaft. The calked projection is provided with an end portion of the small-diameter portion of the rotating shaft abutting on the elastic assembly. The torque changing means is for changing torque. The torque changing means comprises a convexity or concavity formed on the bearing plate portion and the first or the second friction washer on which there are formed a convexity or concavity opposite to the concavity or convexity on the bearing plate portion.
Japanese Unexamined Patent Application Publication of Tokkai No. 2002-266841 or JP-A 2002-266841 (which will be also called Patent Document 3) discloses a tilt hinge which is capable of keeping stable performance for a long period without using lubricant, of facilitating production and assembly, and of allowing the use of inexpensive plated steel sheet as a bearing plate. The tilt hinge comprises a mounting member, a spindle, a movable plate, a first movable friction boss and a first fixed friction boss, a second movable friction boss, a second fixed friction boss, a spring support washer, and a spring washer. The mounting member has a mounting base and the bearing plate. The mounted member is mounted on a fixing portion side. The spindle is journaled not to rotate in a bearing hole. The movable plate is rotatably mounted to the spindle to be movable in an axial direction. The first movable friction boas and the first fixed friction boss are disposed between one side face of the movable plate and the bearing plate so that the first movable friction boas is fixed to one side face of the movable plate and the fixed friction boss is fixed on one side face of the bearing plate. The second movable friction boss is fixed on the other side face of the movable plate. The second fixed friction boss is movable in a spindle direction and is inserted and fixed not to be rotatable. The spring support washer is fixed to the second fixed friction boss. The spring washer is disposed to be brought into contact with the spring support washer. By press-supporting from the other end side of the bearing plate of the spindle to apply load, friction force of each boss acts to control rotating torque of the movable plate thereby to keep an opening/closing portion disposed to the movable plate at an arbitral angle.
Patent Document 3 discloses an example where the movable friction boss has a protrusion and the fixed friction boss has a notch. When the movable friction boss rotates, the protrusion rotates with the protrusion guides along the notch and a rotating range is controlled by restraining the protrusion at both ends of the notch, thereby controlling the rotating range of an open/close portion mounted to the movable plate.
Japanese Unexamined Patent Application Publication of Tokkai No. 2005-326937 or JP-A 2005-326937 (which will be also called Patent Document 4) discloses a tilt hinge which is capable of simplifying and downsizing a friction torque control means. The tilt hinge disclosed in Patent Document 4 is configured of a bracket fixed to equipment main body such as a notebook-sized personal computer, a speed increasing rotary means fixed to the bracket and equipped with a planetary gear, a rotation member such as a display fixed to the input shaft of the speed increasing rotary means, and a friction torque control means disposed between the output shaft of the speed increasing rotary means and the bracket.
Japanese Unexamined Patent Application Publication of Tokkai No. Hei 5-32412 or JP-A 5-324125 (which will be also called Patent Document 5) discloses an angle adjusting device is capable of holding a display part at an optional inclined angle without laying down a display visual field angle adjusting device. In the angle adjusting device disclosed in Patent Document 5, a tilt bracket and a washer are inserted in a tilt spindle and the tilt spindle is crimped on the washer. The tilt spindle has one spindle into which an one-way clutch and an outer wheel are integrated. The outer wheel is provided with a mounted portion for a display case.
Japanese Unexamined Patent Application Publication of Tokkai No. 2004-116275 or JP-A 2004-116275 (which will be also called Patent Document 6) discloses a hinge device using a flange type pipe spring. The hinge device disclosed in Patent Document 6 comprises a first bracket having a pair of axial holes, a pair of flange type pipe springs inserted in the axial holes, a pair of shafts piercingly fitted into through holes of the flange type pipe springs, and a second bracket fixed to one ends of the pair of shafts. At sides where flanges of the pair of flange type pipe springs are positioned, end portions of the pair of shafts are pressure-inserted and fixed to a pair of insertion holes of the second bracket. The first bracket comprises a pair of rising members each having an edge on which an arc-shaped guide groove is formed. The arc-shaped guide groove has a constant angular section (a varying angle of a monitor or the like) on the circumference that has a circular center identical with a rotational center of the shaft. The second bracket has a stopper formed therein. With this structure, it is possible to set (confine) a rotational angle of the hinge device.
In the manner as disclosed in the above-mentioned Patent Documents 1 to 6, conventional tilt hinges, which are used in OA equipment including the liquid crystal display unit, carry out an angular adjustment within a predetermined movable range on moving an angle of the display unit.
Inasmuch as the conventional tilt hinge has one kind of fixed movable range, it is called a movable range fixed tilt hinge.
Herein, there is a case where one of, for example, a first range between 0 degree and 90 degrees and a second range between 0 degree and 40 degrees is required as the predetermined movable range. In this event, it is necessary to prepare two kinds of movable range fixed tilt hinges having different movable ranges. Specifically, it is necessary to prepare a first movable range fixed tilt hinge having a first movable range between 0 degree and 90 degrees and a second movable range fixed tilt hinge having a second movable range between 0 degree and 40 degree. It results in causing a problem such that it becomes high cost.
On the other hand, various prior art documents related to the present invention, each of which is capable of changing a movable range, are known.
By way of example, Japanese Unexamined Patent Application Publication of Tokkai No. 2002-106542 or JP-A 2002-106542 (which will be also called Patent Document 7) discloses a display monitor with a tilting mechanism which is capable of changing a motion angle range even when normally used (when viewed by a user) or maintained. In Patent Document 7, a hinge comprises a coupling member (a shaft) for relatively and rotatably coupling a first member of a stand side with a second member of a monitor body side. The first member has a groove serving as a fitting space for a tilt angle limitation while the second member has a tilt angle limitation projection for movably fitting in the groove. The first member has a stopper projection serving as a moving limitation hitting portion. A cover, which is removable to the stand, has a plate-shaped stopper contact portion at the inside thereof. When normal used, the stopper projection hits to the stopper contact portion. When maintained, the tilt angle limitation projection makes contact with an end portion of the groove. By mounting and demounting the cover, a maximum rotating angle of the monitor body is switched. Specifically, when the cover is mounted, the rotating angle of the monitor body is limited so as to become narrow. When the cover is demounted, the rotating angle of the monitor body is set so as to become wide.
In the above-mentioned Patent Document 7, a removable member (e.g. the cover) is required. When the removable member is demounted, there is a fear to lose it.
Japanese Unexamined Patent Application Publication Tokkai No. 2008-32986 or JP-A 2008-32986 (which will be also called Patent Document 8), which corresponds to U.S. Patent Application Publication No. US 2008/0024750, discloses an image reading apparatus which is capable of simply setting an open/close angle of a document cover of the image reading apparatus at a plurality of stages. In the image reading apparatus disclosed in Patent Document 8, a document cover is located above a document positioning glass plate. The document cover serves as a cover member for pressing a document against the document positioning glass plate and is openably and closably attached to an apparatus body via a hinge member. The hinge member is rotatably supported by a shaft with a hole. A switch member is attached to the apparatus body via a spring. When the hinge member rotates around the shaft, a bump of the hinge member makes contact with a bump of the switch member at a position where the hinge member is open at a rotation angle of approximately 70 degrees with respect to the document positioning glass plate. When the switch member is pressed downward, a clearance is formed that allows the bump of the hinge member to further rotate. As a result, the document cover can be opened via the hinge member to be positioned below the document setting surface of the document positioning glass plate. In this state, the hinge member has the open angle of 180 degrees.
Although the hinge member disclosed in Patent Document 8 mounts the document cover to apparatus body openably and closably, it merely selects the open angle using the switch member. In other words, the hinge member disclosed in Patent Document 8 is different from a tilt hinge for stopping and holding an open/close portion (a movable portion) against a fixed portion at an arbitrary angle within a movable range.